Cleanup: Fluid renaming from old 'manta' naming to new 'fluid' naming

Changed variable names from mmd, mds, mfs, and mes to fmd, fds, ffs, and fes. The author of this commits lights a candle for all the merge conflicts this will cause.

Fluid: Added offset to control frame range

Added an offset field to control when to load the simulation files. Since this is a very small but helpful addition it is in my view safe to commit at this point of the bcon cycle.

Fluid: Fix typos from OpenVDB update

Some typos that were not noticed in 995185894289.

Fix T77204: Mantaflow Initial velocity bugged?

Always initialize the particle velocity of newly sampled particles to 0 if there are no initial velocities. Clearing the grid source makes sure that new particles will get a 0 velocity - and not interpolated from the associated grid.

Fix T77285: Incorrect Mantaflow fluid border interaction when collision is turned off

Incorrect boolean for 'open' domain borders.

Fluid: Use OpenVDB as the default cache format for liquids too

With the updated OpenVDB setup, it is now perfectly fine to use OpenVDB for liquid domains.

Fluid: Fix OpenVDB compiler warnings

Kudos to brecht for noticing the issue

Fix T78213: Windows 10 Build Errors: Extern_Manaflow error messages

Kudos to LazyDodo for figuring this out

Fluid: Updated Mantaflow source with latest OpenVDB changes

This updated set of Mantaflow files includes the improved OpenVDB file IO. With this update it is finally possible to store multiple grids per file. It is also possible to save particle systems and particle data to OpenVDB files.

Fluid: Improved OpenVDB support for fluid caches

This commit makes uses of the new OpenVDB IO in Mantaflow (introduced in 781f783a66ac).

From now on, fluid cache files in OpenVDB format will contain a list of grids per frame (before: one .vdb file per grid per frame). Besides regular grids, particle systems are also stored using OpenVDBs PointGrid data structures.

All older cache formats will remain fully functional:
- Uni caches (.uni) files are still available from the UI and can be used as before
- Raw caches (.raw) are no longer available from the UI, but loading them is still possible
- Old OpenVDB caches (one .vdb per grid) can no longer be baked either, but loading them is still possible.

It is also no longer possible to choose file formats for 'Noise' and 'Particles'. Instead there are now options to set the file format for 'Volumetric' and for 'Mesh' data.

Known issues (planned to be resolved soon):
- OpenVDB files are currently not taking into consideration the clipping value (FluidDomainSettings). Empty cells are therefore being written too. Depending on the scene, this can make file sizes unnecessarily large.
- Domains are not being exported at their world position. Instead they are always clipped to the origin.